Classification and Uses of Ceramics

Classification and Uses of Ceramics

The term ceramics is used to indicate the potter’s art or articles made by the potter.

The ceramics are divided into the following three categories.

1. Clay products

2. Refractories

3. Glass

Clay products

The clay products which are used are tiles, terra-cotta, porcelain, bricks, stoneware’s & earth wares.

Tiles are of two types

(1) Common tile

(2) Encaustic tiles

Types of common tiles

(i) Drain tiles

(ii) Floor or paving tiles

(iii) Roof tiles

Types of roof tiles

Allahabad tiles, Corrugated tiles, Flat tiles, Flemish tiles, Guna tiles, Mangalore tiles, pan tiles.

Refractories

The term refractories is used to indicate substances that are able to resist high temperatures.

Classification of refractories

(i) According to chemical properties.

(ii) According to resistance to temperature.

According to chemical properties

(a) Acidic

(b) neutral and

(c) Basic

(a) Acidic

Fire clay: 

It is used for the manufactured of fire bricks, crucibles, hollow tiles.

Quarizite– For making the silica bricks.

Silica- Coke over and lining for glass furnaces.

(b) Neutral refractory materials

Bauxite- For tire bricks

Carbon- Lining material for furnaces

Chromite- Powerful neutral refractory material.

Forsterite- Used in furnaces for melting copper.

(c) Basic Refractory materials

Dolomite- For making refractory bricks.

Magnesia- Magnesia bricks.

According to resistance to temperature

(a) Low quality

(b) High quality

High quality- Used in modern aeroplanes, rockets, jets etc. Molyblendum, tungsten, zirconium and their alloys are used as the refractory materials.

Cermet – Refractory material containing a combination of clay and metal.

Surface Preparation and Industrial Painting

Reasons of corrosion and surface wear.

The term corrosion is defined as an act or process of gradual wearing away of a metal due to chemical or electro-chemical reaction by its surroundings such that the metal is converted into an oxide.

The corrosion indicates the deterioration and loss of material due to chemical attack.

Following are the factors responsible for corrosion:

(i) Congested reinforcement in small concrete sections.

(ii) Excessive water-cement ratio.

(iii) Improper construction methods.

(iv) Inadequate design procedure

(v) Incompetent supervising staff or contractor.

(vi) Initially rusted reinforcement before placing concrete.

(vii) Insufficient cover to steel from the exposed concrete surfaces.

(viii) Presence of moisture in concrete.

(ix) Presence of salt.

(x) Unequal O2 distribution over the steel surfaces.

Factors influencing corrosion

(i) Blow holes, inclusions trapped gases.

(ii) Chemical nature of the metals.

(iii) Eddy electric currents.

(iv) Presence of dust, dirt.

Purpose of painting and methods of industrial pointing:

Purposes

(i) To protect the surface from weathering effects of the atmosphere and actions by other liquids, fames and gases.

(ii) To prevent decay of wood and corrosion in metal.

(iii) To give good appearance to the surface. The decorative effects may be created by painting and the surface becomes hygienically good, clear, colourful and attractive.

(iv) To provide a smooth surface for easy cleaning.

Ceramics
Ceramics


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